This modules finds all intersection in a set of n boxes in d-dimensions, or between a pair of sets with n and m boxes respectively. The time taken is O((n+m) log^d(n+m)) and the algorithm uses a temporary scratch memory of size O(n+m). This memory is pooled so that after the first execution no additional memory is allocated. Some possible applications of this library include:
- Collision detection
- Polygon clipping
- Batched box stabbing queries
- Mesh boolean operations (CSG)
The algorithm in this package is based on the one described in the following paper:
A detailed experimental analysis of the performance of this module as well as comparisons with other libraries for box intersection can be found in the following repository:
For more information on this problem, please see the following series of blog posts:
Detecting overlaps in a set of boxes
Here is how to detect all pairs of overlapping boxes in a single set of boxes:
var boxIntersect =//Boxes are listed as flattened 2*d length arraysvar boxes =1 1 2 2 //Interpretation: [minX, minY, maxX, maxY]0 -1 3 22 1 4 505 3 1 10//Default behavior reports list of intersectionsconsole//Note: Boxes are closed//Can also use a visitor to report all crossingsvar result =console
overlap: [ [ 0, 1 ], [ 0, 2 ], [ 1, 2 ] ] overlap: [ 1, 1, 2, 2 ] [ 0, -1, 3, 2 ] overlap: [ 1, 1, 2, 2 ] [ 2, 1, 4, 5 ] early out result: 2
You can also detect all intersections between two different sets of boxes:
var boxIntersect =//Again, boxes are given as flattened lists of coordinatesvar red =0 0 0 8 1 1 //Format: [minX, minY, minZ, maxX, maxY, maxZ]0 0 0 1 8 10 0 0 1 1 8var blue =5 0 0 6 10 100 5 0 10 6 100 0 5 10 10 10//Report all crossingsconsole//Again can use a visitor:
crossings= [ [ 0, 0 ], [ 1, 1 ], [ 2, 2 ] ] overlap: [ 0, 0, 0, 8, 1, 1 ] [ 5, 0, 0, 6, 10, 10 ] overlap: [ 0, 0, 0, 1, 8, 1 ] [ 0, 5, 0, 10, 6, 10 ] overlap: [ 0, 0, 0, 1, 1, 8 ] [ 0, 0, 5, 10, 10, 10 ]
Using npm, just run the following command:
npm install box-intersect
This module works in any reasonable CommonJS environment, such as browsersify, iojs or node.js.
var boxIntersect =
boxIntersect(boxes[, otherBoxes, visit])
Finds all pairs intersections in a set of boxes. There are two basic modes of operation for this function:
completewhich detects all pairs of intersections within a single set of boxes
bipartitewhich detects pairs of intersections between two different sets of boxes
The parameters to the function are as follows:
boxesis a list of boxes. Boxes are represented as length 2*d arrays where the first d-components are the lower bound of the box and then the next d components are the upper bound.
otherBoxesis an optional list of boxes which
boxesis tested against. If not specified, then the algorithm will report self intersections in
visit(i,j)is a callback which is called once for each overlapping pair of boxes. If
visitreturns any value not equal to
undefined, then the search is terminated immediately and this value is returned. If
visitis not specified, then a list of intersecting pairs is returned.
visit was specified, then the last returned value of
visit. Otherwise an array of pairs of intersecting boxes.
Note The boxes are treated as cartesian products of closed intervals. For example, the boxes
[0,0,1,1] will be reported as intersecting by this module.
(c) 2014 Mikola Lysenko. MIT License